util-linux mount hook_owner TOCTOU allows local privilege escalation

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Summary

CVECVE-2026-53612
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-14 15:17:20 UTC
Updated2026-10-16 16:00:33 UTC
Descriptionutil-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID `mount` utility's `hook_owner.c` post-mount hook performs path-based `chmod()` and `lchown()` operations on a previously validated mount target. A local low-privileged user authorized by an `/etc/fstab` entry with `user` or `users` and an `X-mount.mode`, `X-mount.owner`, or `X-mount.group` option can use `renameat2(RENAME_EXCHANGE)` to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.

Risk And Classification

Primary CVSS: v3.1 7 HIGH from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-367 | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Util-linux Util-linux affected >= 2.39, < 2.41.5 Not specified
CNA Util-linux Util-linux affected >= 2.42, < 2.42.2 Not specified

References

ReferenceSourceLinkTags
github.com/util-linux/util-linux/releases/tag/v2.42.2 [email protected] github.com
github.com/util-linux/util-linux/commit/d0c5adaeb3a3d823aba1377794de8f00... [email protected] github.com
github.com/util-linux/util-linux/commit/24da33905c7115c4cbccd0afb2a46980... [email protected] github.com
github.com/util-linux/util-linux/commit/897a08c2b11dfa66975c3d24d63c7bf5... [email protected] github.com
github.com/util-linux/util-linux/releases/tag/v2.41.5 [email protected] github.com
github.com/util-linux/util-linux/security/advisories/GHSA-g8wm-75wr-g2vh 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/util-linux/util-linux/commit/722c96974dd4009a334e4aee556eedaa... [email protected] github.com
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